Realistic Nova 8b Rebuild & Crossover Re-Design

videolady201

AK Member-Design Engineer
This was a complete rebuild of a pair of Realistic Nova 8bs! First the cabinets were stripped of all components and cleaned. Then all seams on the inside of the cabinet were resealed with glue. The cabinets were cleaned on the outside and the broke/chipped corners were filled with wood putty and sanded back to shape. The cabinets were then re-laminated with new walnut wood, stained with Golden Oak stain, two coats and then five coats of flat clear was applied. The grill cloth was discarded and the grill frame was cleaned and new cloth was attached. All drivers are stock with no mods of any kind. Raw data was then taken of the impedance of each driver as well as SPL Gated Sweeps and a new crossover was designed. The results are fantastic and this has been more than worth the effort that was put into the speakers. Please see the attached images and the posts following this one.:yes:
 

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Nova 8b Rebuild Continued...

I have included pictures of the back of the Tweeter & Mid Range so you can confirm that your drivers are the same units. The 8bs were known for blowing tweeters as they only had a first order crossover on them. Check your tweeter to be sure it is not blown or damaged. It should read right at 7 ohms on your voltmeter. The mids were not as bad to blow because two units split the load as they are hooked in series. The two together should also be right around 7 ohms on a voltmeter.
 

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Nova 8b Rebuild Continued...

Here are the last two pictures from the set. This is a awesome sounding pair of speakers. The new crossover corrects the lobbing issues between the Tweeter and Midrange units. They were all covering the same bandwidth, which was causing major issues in the vertical and horizontal dispersion of the speaker. Power handling has increased as well, all bands of the crossover are now 12db! :yes:
 

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Nova 8b Rebuild Continued...

Please find in the attachments, the circuit diagram as well as the measurements from the completed system. I will be happy to answer any questions you may have. I think you will love these changes!!!:banana: The graphs show the circuit diagram with the parts value listed for each part, the electrical transfer function of the new crossover, followed by the acoustical transfer function, followed by the impedance with phase and then the Gated SPL of the finished speaker with Phase.

Please NOTE: The tweeter and the mid units must be wired out of phase as shown in the circuit diagram. This is due to their offset in time. This 180 degree shift lines up the time domain with the woofer.
 

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These have an AR-3ish sound to them in stock form, with similar bass. It looks like the mids/highs should be cleaned up nicely with the mods.
 
Mid & Highs

These have an AR-3ish sound to them in stock form, with similar bass. It looks like the mids/highs should be cleaned up nicely with the mods.

They really are cleaned up! Before if you stepped off axis or stood up you would here major changes, and they were not good ones. Now that's gone with much more detail and now with a very open and airy sound and good 3D depth.!:yes:
 
That looks like the response graph from a pair of Paradigm Studio 100s or other current good speaker. Does it sound as good as that graph looks? Is the mids that smooth?

Whats the difference between the mid drivers and tweeters they look the same except for the label.
 
Mids & Tweeter

That looks like the response graph from a pair of Paradigm Studio 100s or other current good speaker. Does it sound as good as that graph looks? Is the mids that smooth?

Whats the difference between the mid drivers and tweeters they look the same except for the label.

It does sound that good! They really do! The mids and Tweeter have the same frame but the magnet on the mid is bigger. The mids also have a lower FS on the driver. From the front you can't tell them apart but there are the two differences as stated. This speaker is good for any kind of music!:yes:
 
Very nice treatment to the cabinets. Did you consider replacing the tweeters? I have a similar RS product the Optimus 5b. I just replaced the stock tweeters with an EPI 1 inch dome tweeter (from a T/E 70). My subjective assessment is that it is better. Not actually an original thought on my part. Other AKers that own the 5b suggested replacement.
 
This was a complete rebuild of a pair of Realistic Nova 8bs! First the cabinets were stripped of all components and cleaned. Then all seams on the inside of the cabinet were resealed with glue. The cabinets were cleaned on the outside and the broke/chipped corners were filled with wood putty and sanded back to shape. The cabinets were then re-laminated with new walnut wood, stained with Golden Oak stain, two coats and then five coats of flat clear was applied. The grill cloth was discarded and the grill frame was cleaned and new cloth was attached. All drivers are stock with no mods of any kind. Raw data was them taken of the impedance of each driver as well as SPL Gated Sweeps and a new crossover was designed. The results are fantastic and this has been more than worth the effort that was put into the speakers. Please see the attached images and the posts following this one.:yes:

Please forgive me if I missed the clue somewhere, but are you a closet Shacker? I thought you were just absorbed with the Mach One, but now I read about Nova speakers as well? I always loved the Shack, nice gear and fair prices, and for the many of us in the real world with limited budgets the Shack kept us happy. Having also worked for the Shack we were accustomed to getting positive feedback on the top end Receivers, Speakers, etc. If BMW is the "driving machine" you'd think everyone would own one, but that isn't the case, different budgets, different driving needs, etc. The same holds true for Audio/Video equipment, which is why I wish the "hardcores" would give it a rest. Constructive criticism OK, but many comments are far from constructive. Glad we have someone like you who, dare I steal a quote, is doing something for the rest of us.

I always liked Nova 7/8 speakers, but it appears you've stepped up the game on these. Maybe down the road the Optimus "T" speakers will be due for some attention?

Play on!!
:thmbsp:
 
Little About RS Stuff

Please forgive me if I missed the clue somewhere, but are you a closet Shacker? I thought you were just absorbed with the Mach One, but now I read about Nova speakers as well? I always loved the Shack, nice gear and fair prices, and for the many of us in the real world with limited budgets the Shack kept us happy. Having also worked for the Shack we were accustomed to getting positive feedback on the top end Receivers, Speakers, etc. If BMW is the "driving machine" you'd think everyone would own one, but that isn't the case, different budgets, different driving needs, etc. The same holds true for Audio/Video equipment, which is why I wish the "hardcores" would give it a rest. Constructive criticism OK, but many comments are far from constructive. Glad we have someone like you who, dare I steal a quote, is doing something for the rest of us.

I always liked Nova 7/8 speakers, but it appears you've stepped up the game on these. Maybe down the road the Optimus "T" speakers will be due for some attention?

Play on!!
:thmbsp:

In my living room I have one of our reference systems. Mono Block Tube Amps and Tube Pre with Our top of the line Speakers all wired with the Cardas Golden Refence cables. I know good sound. What is shocking is how good these modded Nova 8bs with an STA-225 are!! I very much enjoy my time listening to them and would even say they have now made it into the ballpark!
 
That's very impressive!

It's a revelation to see that the woofer plays nicely up to ~1.6kHz.
That will surely tempt some to econowave their Nova 8Bs and Optimus 5Bs. But your crossover mod now offers an option to greatly improve this good speaker for those who prefer to keep their drivers stock.

I'm predicting these 8Bs and 5Bs will become more popular than they already are.
 
Stock Drivers

That's very impressive!

It's a revelation to see that the woofer plays nicely up to ~1.6kHz.
That will surely tempt some to econowave their Nova 8Bs and Optimus 5Bs. But your crossover mod now offers an option to greatly improve this good speaker for those who prefer to keep their drivers stock.

I'm predicting these 8Bs and 5Bs will become more popular than they already are.

The stock drivers are better than most would think. It is the crossover that is giving the problems. With the right crossover most would be surprised how good those drivers are!!:yes: They have very high-compliance and very low FS that is out of the band used by the new crossover, making them very neutral.
 
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Mods for Nova 8bs

I am hoping someone will do these mods. You will not believe the results!! Do one and compare it to the stock unit. With both get on axis and listen and then move off axis with each. Compare the resolution, depth, low level decay, openness, etc. Not only will you find the difference in the mid and highs but the transparency of the bass as well. Who will be the first to enjoy the speakers the way it can perform?? I would like to hear from you, if I can get you to quit listening for a few, after the mods!!:D
 
I have a pair of 5's (not b) and I may be interested in this mod. I'd have to check to make sure the drivers are the same as the 8b (I'm pretty sure the woofer is). My problems are:

1. The tweeters on mine are dead- currently using some vifa domes. Would the vifa's work in this case or should I hunt for the original tweeters?

2. I've never assembled a cross-over before so I would need a lot of hand-holding.

3. If they sound as good as you say I would have to re-laminate my cabinets as they look pretty bad now (my problem).

I have to say with the new capacitors and the vifa tweeters I put in these Optimus 5's they sound pretty good. If they improve as you say then sounds like they are one heck of a speaker after the mods.

Tiga


I am hoping someone will do these mods. You will not believe the results!! Do one and compare it to the stock unit. With both get on axis and listen and then move off axis with each. Compare the resolution, depth, low level decay, openness, etc. Not only will you find the difference in the mid and highs but the transparency of the bass as well. Who will be the first to enjoy the speakers the way it can perform?? I would like to hear from you, if I can get you to quit listening for a few, after the mods!!:D
 
With just about any vifa tweeter you'd be a step ahead of the curve. You'd need a custom crossover done to make the most of the new tweeters.
 
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